The invention pertains to dental instruments. More particularly, the invention pertains to dental instruments which have reinforced, molded handles.
Hand held dental instruments include an elongated shaft for gripping and manipulation by the dental practitioner and a tool or point located at one or both ends of the shaft. The tool or point is typically a stainless steel or other metallic material. The shaft is typically a stainless steel shaft, or a molded plastic shaft, or a molded plastic shaft having a central metal tube for reinforcement.
The tools or points can be inserted into metallic cones having receiving sockets for receiving a base of the tool. The cones can be brazed or welded to metal handles or metal reinforcing tubes. Alternatively, they can be insert molded or adhesively secured to a plastic handle. Examples of handle constructions are disclosed in U.S. Pat. Nos. 5,816,806; 5,501,597 and 4,882,867.
While the dental instruments having the metal shaft, or the metal tube reinforced plastic shaft, offer strength advantages, the techniques used to attach the tool parts are relative costly. The present inventor has recognized that it would be advantageous to provide a molded plastic handle with a metal reinforcing tube for a dental instrument, which handle carries one or more tool parts, wherein the tool parts can be effectively and securely attached to the handle.
A dental instrument includes a plastic elongated body having an elongated, metal, reinforcement extending through the body. The reinforcement includes at least one, and preferably two, hollow ends.
One, and preferably two working members, each of which has an affixing stem and an attached functional portion, are attached to the reinforcement. Particularly, the respective stems slide into the hollow ends and are adhesively attached to the reinforcement.
According to the preferred embodiments of the invention, the reinforcement comprises a hollow tube or rod. Each stem includes at least one glue trap.
During assembly, glue is applied in the hollow end of the reinforcement and the stem glue trap xe2x80x9ccapturesxe2x80x9d the glue as it is press fit into the reinforcement. Alternatively, the glue can be applied to the glue trap and the stem is press fit into the respective hollow end of the reinforcement.
According to the preferred embodiments, the working member comprises a tool having a tapered external surface which terminates in a blocking shoulder. When the stem is press fit into the hollow end of the reinforcement, the shoulder abuts the end of the reinforcement.
The plastic body of the handle can have a molded, contoured or knurled surface for assisting with gripping manipulation of the instrument by a dental practitioner. This is particularly important considering that the practitioner may be wearing surgical gloves which can become slippery with a patient""s saliva. The contoured surfaces are also preferably sufficiently xe2x80x9croundedxe2x80x9d or xe2x80x9cdulledxe2x80x9d to prevent the possibility of cutting a surgical or latex glove.
Adjacent to each tool at the ends of the handle, the plastic body is tapered toward the functional portion to provide a gripping and manipulation surface for the practitioner. Annular grooves are provided on these tapered ends to increase traction.
The molded contoured surfaces can be manufactured in a mold having only a single parting plane. This is accomplished by providing a contoured surface having raised elements over substantially the entire circumferential surface of the contoured regions, except that at the sides of the body the contours are circumferentially smooth, i.e., having no undercuts or axial cuts. This configuration permits the mold halves to be parted and separated along the single plane so the body can be removed from the mold.
Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings.